1. Field of the Invention
The present invention relates to communication session control in a communication system, and in particular, but not exclusively, to control of a communication session established over a packet data network between a user equipment and another party.
2. Description of the Related Art
A communication system can be seen as a facility that enables communication sessions between two or more entities such as user equipment, controllers and/or other nodes associated with the system. The communication may comprise, for example, communication of voice, video, data, multimedia and so on. An application session may, for example, comprise a two-way telephone call or multi-way conference session or connection between a user equipment and an application server (AS), such as a service provider server or proxy. The establishment of communication sessions generally enables a user to be provided with various services.
Signalling between various entities associated with a communication session is typically required in order to control the communication session. Control is typically required for the set-up of the communication session and also later on during communication on the established communication session. The signalling can be based on an appropriate communication protocol or protocols.
The communication may be provided by fixed line and/or wireless communication interfaces. An example of the fixed line system is a public switched telephone network (PSTN). The wireless communication may be provided by means of a mobile communication system. Mobile communication systems refers generally to any telecommunications systems which enable a wireless communication when users are moving within the service area of the system. An example of a typical mobile communication system is a Public Land Mobile Network (PLMN).
The mobile communications network can provide an access network providing a user with a wireless access to external networks, hosts, or services offered by specific service providers. The user may need to have a subscribership with the mobile communications system in order to be able to use the services of the mobile system. The mobile subscription information of the subscriber may indicate parameters such as parameters regarding the quality of service (QoS) the subscriber is entitled to receive, priorities, service restrictions, security, authentications, and so on.
An access point or gateway node of the mobile communication network provides further access to an external network or an external host. For example, if the requested service is provided by a service provider located in another network, the service request is routed via a gateway to the other network and the service provider. The routing may be based on definitions in the mobile subscription information stored in the mobile network.
A more detailed example will now be described with reference to general packet radio service (GPRS). The GPRS operational environment comprises one or more subnetwork service areas, which are interconnected by a GPRS backbone network. A subnetwork may comprise a number of packet data service nodes (SN). In this specification the service nodes will be referred to as serving GPRS support nodes (SGSN). Each of the SGSNs is connected to radio networks, typically to base station systems and/or radio access networks by way of base station controllers (BSC) and/or radio network controllers (RNC) in such a way that they can provide a packet service for mobile user equipment via several base stations, i.e. cells. The intermediate mobile communication network provides packet-switched data transmission between a support node and mobile user equipment. The subnetworks are in turn connected to an external data network, e.g. to a packet data network (PDN), via GPRS gateway support nodes (GGSN). The GPRS thus allow transmission of packet data between mobile user equipment and external data networks.
A packet data protocol (PDP) context may be established to carry traffic flows over the communication system. A PDP context typically includes a radio access bearer provided between the user equipment, the radio network controller and the SGSN, and switched packet data channels provided between the serving GPRS service node and the gateway GPRS service node. A session between the user equipment and other party would then be carried on the established PDP context. A PDP context can carry more than one traffic flow, but all traffic flows within one particular PDP context are treated the same way as regards their transmission across the network. This requirement regarding the similar treatment is based on PDP context treatment attributes associated with the traffic flows. These attributes may comprise, for example, quality of service and/or charging attributes.
In GPRS networks, the mobile user equipment may optionally indicate, in a message requesting to activate a packet data protocol (PDP) context in the network, an access point name (APN) for selection of a reference point to a certain external network. A Serving GPRS support node (SGSN) may authenticate the mobile user and send a PDP context creation request to a gateway node (GGSN) selected e.g. according to the access point name given by the user equipment, or to default GGSN known by the SGSN.
Various features can be controlled by the serving controller entity, such as the SGSN, during a communication session. This control may be based on information associated with the subscription and stored in a dedicated subscriber information database. A well known example of the subscriber information database is a home location register (HLR). Another example is a home subscriber server (HSS).
Various user equipment (UE) such as computers (fixed or portable), mobile telephones and other mobile stations, personal data assistants or organizers, and so on are known to the skilled person. These all can be used to access the packet data networks, e.g. corporate intranets or the Internet, to obtain services. Mobile user equipment, typically referred to as a mobile station (MS), can be defined as a means that is capable of communication via a wireless interface with another device such as a base station of a mobile telecommunication network or any other station. The increasing popularity of Third Generation (3G) communication systems will, in all likelihood, significantly increase the possibilities for accessing services on the packet data networks via mobile user equipment (UE) as well as other types of LE.
The term “service” used above and hereinafter will generally be understood to broadly cover any service or goods which a user may desire, require or be provided with. The term also will generally be understood to cover the provision of complementary services. In particular, but not exclusively, the term “service” will be understood to include browsing, downloading, email, streaming services, Internet Protocol multimedia (IM) services, conferencing, telephony, gaming, rich call, presence, e-commerce and messaging, for example, instant messaging.
In the conventional communication systems, the control features are set and controlled by the serving controller node based on the subscription information stored at the subscriber information database or based on pre-configured settings in the serving controller node.
It might, however, be advantageous if, when controlling communication sessions at the access network side, the control could take into account the service requirements set forth by one or more other factors rather than just the subscription information.
It might also be advantageous in certain instances to be able to dynamically modify communication session treatment such as the quality of service (QoS) attributes and/or specifically the Allocation/Retention Priority (ARP) based on the requirements of the services for which the communication session is established. This is not possible in the current networks to the extent that is required in order to ensure sufficiently reliable operation of the system. For example, certain QoS attributes may only be downgraded from the values set by the user equipment, subscription information and/or pre-configured settings in the serving controller node. In addition, certain QoS attributes may not be modified at all within the system. For example, when an ARP value is set in the HLR for a subscriber's PDP context, this value cannot be modified within the system at all. In this example, modifying the ARP value may result in error cases in the elements within the system, e.g. in the SGSN. Because of these limitations, it may not be possible to upgrade QoS or modify the ARP at all with the prior art SGSN and GGSN arrangements.
As a more practical example, in the GPRS based systems, the SGSN may reserve resources for real-time PDP contexts as soon as it is possible, i.e. before signalling with the GGSN. The SGSN may then later modify the resource reservation in the instance that the QoS is downgraded by other elements of the system. The downgrading may be initiated, for example, by the GGSN or by the RNC.
The risks of error cases are increased because the SGSN operates based on subscription information and/or pre-configured settings, such as QoS restrictions and ARP values stored in the HLR, while the GGSN may operate based on service requirements. This may result to situations where the service would require attribute values from the GGSN that are not allowed for the subscriber by the HLR and/or the SGSN.
It could also be advantageous to have a policy controlling mechanism that could be used for a number of different services, and not just, as in the prior art, for one type of services, such as the IM services.